Four Oyabun Rengo

The Four Oyabun Rengo is unique among the Yakuza as they control a AAA megacorporation, the Mitsuhama Computer Technologies via their ownership of nearly half the shares. It's a syndicate that is solidly neutral in the ideological conflict between the Old School and New Way Yakuza.

What remained of their gumi were absorbed either into MCT itself or into their respective household staffs. Mitsuhama deals with whichever Yakuza has territory or operations that overlap with the interests of MCT. Like any other Japancorp they use the Yakuza to advance their interests and in exchange they function as one of the world's biggest money launderers for the Yakuza.[2]

The Four Oyabun were originally Mita-gumi under-bosses, and though they are now among the
richest men on Earth, they still have obligations to their fellow Yakuza.[3]